CHM 1120 EXAM II SECTIONS 004/005 03/19/14

Name:___Dr. Timothy M. Trygstad Answer Key_____

Score:__100__/ 100

(please write your NAME above AND on the last page of this exam!!!)Be sure to show all of your work clearly (partial credit) and circle your final answers.Dont forget to label your answers with the correct units when appropriate.1. Which of the following reactions is correct for a strong acid, HA, in water? (3 pts.)a)b)c)d)e)

HA + H3O+ H2O + AHA + H2O H3O+ + AHA + H2O HO- + H2A

HA + H3O+ H2O + Anone of the above (HA + H2O H3O+ + A-)

2. Which of the following is not a strong base? (3 pts.)

a)b)c)d)e)

LiOHBa(OH)2NaOHMg(OH)2Ca(OH)2

3. The pH of an aqueous Ba(OH)2 solution is 12.85, what is the concentration of the Ba(OH)2 solution? (3 pts.)a)b)c)d)e)

1.41 x 10-13 M0.0354 M0.0708 M0.1416 Mnone of the above

4. What is the pOH of a solution with a [H3O+] of 5.88 x 10-9 M? (3 pts.)

a)b)c)d)e)

1.005.768.2413.00none of the above

5. Which of the following weak acids has the weakest conjugate base? (3 pts.)a)b)c)d)e)

11. Calculate the Kb of HSO3- and compare it to its Ka to determine if it is a stronger acid or base. (4 pts.)

12. If you added 200 mL of 0.5625 M NaOH to this sulfurous acid solution, which of the four titration stageswould you be at and describe how you would solve for the pH at this point in the titration? (5 pts.)

One would realize that you have equal moles of weak acid and strong base, thus, they would both be completelyconsumed and you would produce and equivalent amount of the conjugate weak base (HSO3-). One would thenneed to use and ice chart to assist in completing the equilibrium expression for the ionization of this newlyformed weak base in order to solve for the amount of either [H3O+] or [HO-] and then use the happy funwheel to convert either of those concentrations into pH.SPRING 2014, CHM 1120, SECTIONS 004/005, EXAM II, PAGE 3 of 8